The present application is based on and claims priority to Japanese Patent Application No. 2000-338815, filed Nov. 7, 2000, which is hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to an improved arrangement for an outboard motor, and more particularly to an improved arrangement for a four-cycle engine of an outboard motor.
2. Description of the Related Art
A typical outboard motor comprises a power head and a housing depending from the power head. The power head includes an internal combustion engine that drives a marine propulsion device (e.g., a propeller) through a driveshaft and a propulsion shaft, which are both journaled within the housing. The marine propulsion device is attached to the end of a propulsion unit, which extends from housing and is in a submerged position.
The internal combustion engine is typically covered by a protective cowling. The protective cowling typically comprises an upper portion and lower portion, which are removably mounted to each other by hooks or other coupling mechanisms, such as, for example, hooks. Accordingly, the upper portion can be removed from the lower portion such that the engine can be inspected and/or repaired. A general problem associated with outboard motors is that it is generally desirable to keep the height and width of the protective cowling as small as possible. As such, the space within the cowling is extremely limited. In this limited space, many engine components must be disposed.
There is an increasing emphasis on obtaining more effective emission control, better fuel economy and, at the same time, continued high or higher power output in outboard motors. Accordingly, four-cycle engines have started to replace two-cycle engines in outboard motors. In a similar manner, it has been suggested that direct fuel injection be used in outboard motors to further reduce emissions and improve performance. However, to date, it has been difficult to arrange all the components of a direct-injected four-cycle engine into the limited of space of an outboard motor cowling.
Accordingly, one aspect of the present invention is a four-cycle engine for powering an outboard motor. The engine comprises a plurality of combustion chambers arranged generally vertically above one another. The combustion chambers are formed by at least an engine body, a cylinder head assembly and a piston that moves relative to the engine body and the cylinder head assembly. A crankshaft that extends in a generally vertical direction is coupled to the piston such that movement of the piston causes the crankshaft to rotate. At least one air intake port and at least one exhaust port communicate with the combustion chamber. An intake valve moves between an open and closed position. An exhaust valve moves between an open and closed position. An valve actuating mechanism includes an intake camshaft capable of moving the intake valves and an exhaust cam shaft capable of moving the exhaust valves. A head cover assembly covers the valve actuating mechanism and defines, at least in part, a cam chamber. A fuel injection system comprises a fuel injector communicating with each combustion chamber and arranged to deliver fuel directly to the combustion chamber. The fuel system also includes a fuel pump that communicates with at least one of the fuel injectors. The fuel pump is actuated, at least partially, by rotation of the intake cam shaft or the exhaust cam shaft and is positioned at least partially within the cam chamber.
Another aspect of the present invention is a four-cycle engine for powering an outboard motor. The engine comprises a plurality of combustion chambers arranged generally vertically above one another. The combustion chambers are formed by at least an engine body, a cylinder head assembly and a piston that moves relative to the engine body and the cylinder head assembly. A crankshaft that extends in a generally vertical direction is coupled to the piston such that movement of the piston causes the crankshaft to rotate. At least one air intake port and at least one exhaust port communicate with the combustion chamber. An intake valve moves between an open and closed position. An exhaust valve moves between an open and closed position. An valve actuating mechanism includes an intake camshaft capable of moving the intake valves and an exhaust cam shaft capable of moving the exhaust valves. A head cover assembly covers the valve actuating mechanism and defines, at least in part, a cam chamber. A fuel injection system comprises a fuel injector communicating with each combustion chamber and arranged to deliver fuel directly to the combustion chamber. The fuel system also includes a fuel pump that communicates with at least one of the fuel injectors. The fuel pump is located at partially within the cam chamber and is positioned generally between adjacent cylinder. The fuel pump has a longitudinal axis that is slanted towards a cylinder axis extending through the adjacent cylinders.